The shoulder joint is the most mobile and flexible joint in the human body. This joint controls the position of the upper arm and, due to the high flexibility of the joint, enables a tremendous range of motion. However, due largely to its high flexibility, the shoulder is frequently subject to injury leading to pain, inflammation and loss of motion. The humerus and the scapula are the two major components of the shoulder joint with a portion of the head of the humerus functioning substantially as a ball positioned in a rather shallow cup-like area of the scapula known as the glenoid fossa. Smooth articular cartilage covers both the head of the humerus and the glenoid fossa and, together with the action of synovial fluid, allows these surfaces to glide with little friction. The joint capsule comprised of strong ligaments connects the head of the humerus to the scapula at the glenoid fossa so as to both secure and help define the joint and resist dislocation.
Muscles attached to different parts of the shoulder are utilized to enable the upper arm to move. The deltoid is a large muscle attached medially to the scapula along the acromion and also attached to a portion of the clavicle. The lateral portion of the muscle crosses the shoulder joint and is attached to the humerus about halfway down its length. The deltoid is the strongest of the shoulder muscles. Its function is to raise the arm upward (or abduction).
Internally disposed in relation to the deltoid muscle, a group of muscles known as the “rotator cuff” helps stabilize the joint as well as enable further movements of the arm. More specifically, the rotator cuff is a group of four muscles forming a strong “cuff” about the joint formed by the head of the humerus and glenoid fossa. In addition to helping to stabilize this joint, these muscles provide rotation and stabilize position of the arm. The four muscles of the rotator cuff are the subscapularis; supraspinatus; infraspinatus and teres minor.
The subscapularis muscle is attached to the deep surface of the scapula and then passes in front of the humeral head. It inserts into the humerus at the lesser tuberosity. This muscle is used to internally rotate the shoulder (and arm) and to bring the arm down to the side of the body (a motion that is called “adduction”). Ordinarily, internal rotation of the shoulder, or abduction, results in rotation of the arm so that the palmar surface of the hand turns away from the body as the dorsum of the hand approaches the trunk. For example, internal rotation of the right shoulder ordinarily results in a counter-clockwise rotation of the right hand and internal rotation of the left shoulder results in a clock-wise rotation of the left hand.
The three remaining muscles of the rotator cuff each have medial insertions at posterior surface of the scapula and then extend posterior to the humeral head where each continue on to insert at the greater tuberosity of the humerus. Such insertions and path enable these muscles to externally rotate the shoulder (and, in regard to supraspinatus) abduct (or move the arm outward, away from the side of the body).
Each of the muscles of the rotator cuff are susceptible to injury such as sprains and muscle tears which can be debilitating. The supraspinatus muscle and tendon is especially susceptible to such injury and is the most commonly injured part of the rotator cuff due, in large part, to its position and path of contraction. However, any of these muscles and associated tendons can an are involved in rotator cuff injuries.
It is known that strengthening the rotator group of muscles through exercise can greatly reduce the chance of rotator cuff injury and/or re-injury. For this reason, it is also well known to perform internal and external rotations of the shoulder to keep these muscles in top condition. Such exercise is also utilized as part of rehabilitation programs for treatment of rotator cuff injuries. More specifically, such rehabilitation programs often progress from passive range of motion exercises to active-assisted range of motion exercise to strengthening exercises.
Mastectomy patients often suffer shoulder pain related to cervical radiculopathy. Such underlying conditions may be exacerbated by the surgical procedures. Nonetheless, post operative shoulder pain is quite common in breast cancer patients during all phases of the disease.
Radiculopathy may present as pain, paresthesias, numbness, or weakness of the shoulder, arm, and/or hand. In particular, upper cervical radiculopathy (C5 or C6) commonly radiates pain to the shoulder and upper arm and weakens the rotator cuff muscles, biceps, and deltoid. Shoulder pain/rotator cuff weakness can contribute to shoulder impingement and secondary adhesive capsulitis. Non-cancer-related cervical radiculopathy can be treated nonoperatively with physical therapy (PT), anti-inflammatory drugs, and nerve-stabilizing agents such as gabapentin. Malignant radiculopathy can respond to similar interventions but may also require chemotherapy, external beam radiation, or surgery. PT and occupational therapy (OT) can improve upper extremity strength, dexterity, coordination, activities of daily living, and shoulder range of motion (ROM) and decrease neck spasms. This is true even when symptoms are caused by cervical primary or metastatic cancer. In the absence of mechanical instability, significant epidural disease (which could result in spinal cord compression), or progressive neurologic deficits (an indicator of spinal cord or nerve root compression), therapeutic activities including active and passive ROM exercises are generally safe. Thus, it would be highly advantageous for such individuals to be provided with a safe and effective device for providing such ROM and shoulder strengthening exercises. (See Stubblefield M D, Custodio C M. Upper-extremity pain disorders in breast cancer. Arch Phys Med Rehabil 2006; 87(3 Suppl 1):S96-9.)
In the past, strengthening exercises for the rotator cuff muscles—including those used for rehabilitation and for prevention of injuries—included external rotation and internal rotation of the shoulder utilizing, for example, hand weights. Utilizing such weights, an individual might, for example lie on their side on the floor or a exercise bench with their upper arm parallel to their body and lower arm held 90 degrees in relation to the upper arm. Thereafter, the shoulder could be internally or externally rotated, while holding a weight, to perform resistive training.
Utilizing free weight exercise was of limited value in that, depending upon the user's position, it is difficult to obtain consistent resistance through, for example, a complete 180 degrees of internal or external rotation. A handheld weight, following an arch-like movement, will not provide consistent resistance. For example, when the user's shoulder is positioned so that the lower arm lies vertical (plumb), there is substantially no force exerted upon the rotator cuff muscles. However, as the shoulder rotates and the lower arm approaches a position parallel with the floor, the force provided by the weight acting upon the rotator cuff muscles will increase. Such exercises also require utilizing different barbells when greater or lesser resistance is required. Such techniques also make no allowance for control and achievement of a safe range of motion. Holding a free weight by hand, especially in regard to a rehabilitation exercise, may be dangerous in that the potential energy associated with the weight might cause a user to over-extend his or her movements —go beyond a range of motion in which such movement is safe—. Such free weight exercises make no provision for controlling range of motion (ROM). Also, if a user should suffer a spasm, sudden pain or lose consciousness, the potential energy stored in the free weight or the momentum developed could cause further injury to the user or others. In addition, performing both internal and external rotation of the shoulder with weights would most likely require a user to continually change position.
It has also been known, in the past, to utilize elastic bands and pulleys to exercise the muscles of the rotator cuff. More specifically, internal and external rotations of the shoulder have been accomplished utilizing an elastic band (or tube) fixed to a support, such as a door or pole. In such exercise, the individual may stand, sit or kneel, with her upper arm aligned with her torso and lower arm positioned at about 90 degrees in relation to the upper arm. Thereafter, the user grasps the free end of the tube or band and performs the desired rotation which is resisted by the elastic material. However, utilizing such an exercise device subjects a user to varying amounts of resistance as the band or tube is stretched and, similar to the use of weights, subjects the user to the danger of stored potential energy within the elastic posing a danger of injuring the user. Also, such elastics require the user to change position when he or she wishes to change from internal to external rotation exercises.
Pulley devices utilizing weights have also been known to be utilized for performing internal and external rotation shoulder exercises. However, as the case with hand weights and elastics, pulley machines also store potential energy during use which can result in the aforementioned injuries. Such machines also require a change in user position and/or machine configuration in order to perform both internal and external rotation exercises.
U.S. Pat. No. 4,878,663 discloses a rehabilitation and fitness apparatus which incorporates a range limiter disc. The disclosed device utilizes a rotating disc which is rotated through the action of an actuator arm. However, rather than using the range limiter disc to control the range of movement a user's shoulder could internally or externally rotate, the disclosed device uses the disc to set the actuator bar in a desired “start” position so as to enable one machine to be utilized to perform multiple exercises (such as internal and external shoulder rotation). The disclosed device utilizes a stack of weights to provide resistance to a user's motion which, of course, does entail the storing of potential energy and generation of momentum that can cause the aforementioned problems. The device does provide adjustment of resistance by the use of a pin to control the number of weights in the stack utilized.
U.S. Pat. No. 4,957,281 discloses a rotator cuff therapeutic exercise device which includes a stack of weights supported by a frame which are raised in a working stroke from a rest position, against gravitational force, to a raised position (with stored potential energy). An actuator mechanism on the frame is specifically shaped and configured to be gripped and rotated by the hand of a user to move the weights along the working stroke. The actuator mechanism may be adjusted to a first or second position for enabling a corresponding rotational working motion of the one of the user's arms whose hand grips the actuator mechanism. This device, as discussed above in regard to free weight exercise and elastic resistance machines, stores potential energy and develops considerable momentum which may be damaging to a user and includes no means of controlling the range of motion during inward or outward rotation. The machine also requires manual adjustment to change resistance.
U.S. Pat. No. 5,080,350 discloses a rehabilitation/exercise device wherein elevational adjustment is provided. However, the device disclosed in this patent provides no means to provide limitation to internal or external rotation of a shoulder. The subject device utilizes a brake and brake drum to provide resistance.
Ideally, a shoulder rehabilitation/exercise device should: a. enable an individual to perform internal and external rotations of the shoulder wherein the device: b. enable performance of inward and outward rotations of both the right and left shoulders without having to adjust the device or re-position the user; c. provide secure, stable, and adjustable positioning of a user's elbow; d. provide adjustment to accommodate arm's of varying length; e. provide adjustment of the angle formed between the upper and lower arm; f. provides a means of controlling the range of motion a user may operate the device during such operation; g. provide fluid-like resistance during exercise so as to prevent injury to the shoulder joint; h. exerts no substantial force which would otherwise continue movement of the device after a user has terminated operation thereof; I. enable adjustment of device resistance without having to manually adjust the device; and j. enable manual adjustment in regard to device resistance when such is advantageous.
U.S. patent application Ser. No. 12/156,199, (hereinafter referred to as “the '199 application”) discloses, a highly portable shoulder rehabilitation and exercise device requiring no external source of power and which is operated by the physical effort of a user alone. Operation of the device enables a user to accomplish both internal (inward) and external (outward) rotations of both the right and left shoulder joint—without having to adjust the device or the user's position—while providing smooth, fluid-like operation. The device disclosed in U.S. patent application Ser. No. 12/156,199 enables a user to suddenly terminate such rotation without potential energy or momentum generated by the device being sufficient enough to oppose such termination. The disclosed device also provides secure, stable retention of a user's elbow while also providing adjustment to accommodate arms of varying dimensions and enabling setting forth a desired angular relation between a user's upper and lower arm. However, the means utilized to adjust the angular relation of a user's upper and lower arm disclosed in U.S. patent application Ser. No. 12/156,199 necessarily changes the amount of force required to operate the device (at a given rate of speed) due to the effect of such adjustment lengthening or shortening the moment arm—or the effective length of the lever—of the below described actuator arm. The device disclosed in U.S. patent application Ser. No. 12/156,199 also enables positive limitation of the range of inward and outward rotation of a user's shoulder during use of the device. Also, the device enables smooth, fluid-like resistance to internal or external rotation which is automatically increased as a user applies greater force to internal and external rotations. In certain preferred embodiments of the '199 application, the device includes a means to manually vary resistance to internal and external rotation while also automatically adjusting resistance in accordance with the force applied by a user. It would be highly advantageous if a shoulder exercise/rehabilitation device could be disclosed which incorporated all of the advantages provided by the '199 device, such as, for instance:
1. providing inward and outward resistance exercises for the shoulder with fluid like motion;
2. enabling a user to stop exercise motion without having to overcome stored potential energy;
3. providing positive range of motion measurements/stops; and
4. providing adjustable resistance
while, at the same time, providing the ability to change the relative elevation of the actuator arm to which a user applies force—without such changes in elevation causing a change in the effort necessary to move the actuator arm at any given speed. To put it simply, the shoulder exercise/rehabilitation device of the '199 patent enables a user to change the elevation of the disclosed actuator arm in order to provide a desired angular relationship of the upper and lower arm of a user (or to accommodate the height of a user's chair or table). That device provides elevation changes via a pivoting relationship between the actuator arm which a user grips with his/her hand, and the restrictor arm which connects the actuator arm with a rotary damper. Such elevation, as discussed below, necessarily shortens the distance between the point along the length of the actuator arm where an operator grips the grip handle and the longitudinal axis of rotation—thus decreasing the distance between the point of force application (the hand grip) and the longitudinal axis of rotation. Thus, as the actuator arm of the '191 application rises, the effective leverage provided by the arm decreases and the amount of torque required to operate the device increases. Therefore, the '191 device is unable, without the use of additional adjustments, to provide a uniform resistance for a user as the elevation of the actuator is adjusted to accommodate a particular user's arm dimensions or the height of a table and/or chair utilized when operating dame. What is needed is a means of changing the relative elevation of the actuator arm in relation to the planar surface of the surface to which the device is affixed, without effecting and/or changing the effective length of the lever arm provided by the actuator arm.